As cataracts is the main cause for blindness, a phone accessory that diagnoses cataracts could cut down on blindness, particularly in the developing world. As shown in the video here, MIT's CATRA is a low-cost solution which not only detects cataracts, but also tracks the severity of them over time.

Thanks to the low-cost supplies the eyepiece is made from, and the fact that smartphones are becoming more common in developing worlds, MIT is hopeful that like Joshua Silver's self-adjustable glasses, CATRA can make a real change in people's lives. [MIT via Cnet via Make]